Sheet metal hub assembly

ABSTRACT

A method of manufacturing a hydraulic torque converter impeller member and the product of such manufacture in which a hardened steel cylindrical bearing is assembled to a drawn hub portion of a generally annular sheet metal part to comprise a torque converter impeller comprising the steps of (1) semidrawing the part to include a partly drawn hub portion, (2) placing a hardened cylindrical bearing in a die mechanism, (3) assembling the generally annular part into the die mechanism with the hub portion engaged in the cylindrical bearing (4) drawing and extruding the hub by moving an object the size of the desired finished inside diameter of the hub through same whereby the hub is formed and forced against the bearing member with sufficient force to make a permanent connection between the hub and bearing, and (5) trimming the excess material from the outer end of the hub portion to conform same to the dimensions of the cylindrical bearing.

This is a division of application Ser. No. 598,441 filed July 23, 1975,now U.S. Pat. No. 3,981,068 issued Sept. 21, 1976.

SUMMARY OF THE INVENTION

It has been known for sometime that one of the most economical ways tomanufacture component parts for a hydraulic torque converter is tomanufacture same from sheet metal rather than from die castings orotherwise. The problem which presents itself when manufacturing theimpeller member of a hydraulic torque converter from sheet metal andparticularly when the hub portion of the impeller member, which includesboth a bearing support and drive mechanism for a fluid pump, is formedfrom the sheet metal of the impeller member, is that the hub has poorbearing characteristics and that it is expensive and extremely difficultto provide a hardened surface on the sheet metal hub suitable forbearing purposes. The present invention provides a product comprising animpeller member with a unitary hub portion thereon out of sheet metalwhich includes a thin cylindrical hardened steel bearing assembled tothe sheet metal hub portion. The assembly of the cylindrical bearing tothe hub portion is by a unique drawing and extruding process comprisingplacing the bearing in a die, assembling the partly finished sheet metalimpeller member in the die with the hub portion thereof in partlyfinished form engaged within the bearing, and passing a hardened steelor carbide ball through the center of the hub portion thereby drawingand extruding the hub through the cylindrical bearing to permanentlyconnect or assemble the bearing to the hub portion. In this manner in arelatively inexpensive way, a proper bearing surface is provided on thesheet metal hub of the torque converter impeller member.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view through an impeller member of a hydraulictorque converter showing the hub assembly of the present invention;

FIG. 2 is a perspective view of the hub portion of the impeller of FIG.1; and

FIGS. 3 and 4 are partial sectional illustrations of the forming stepsin securing the bearing member to the hub portion.

Referring to FIG. 1, an impeller member 10 is illustrated whichcomprises a generally annular member 12 made of sheet metal having a hubportion 14 thereon. A plurality of sheet metal blades 16 are securedwithin the impeller member 10 as is known in the prior art to providefor the pumping of fluid within a hydraulic torque converter of whichimpeller 10 is a component part. For a more complete description of atorque converter of this nature reference may be had to U.S. Pat. Nos.2,717,673 and 2,855,852 of common assignee.

The hub portion 14 has a hardened cylindrical bearing 18 thereon whichis adapted to provide a wear surface for rotation of the impeller 10 ina transmission mechanism. A pair of drive slots 20 are provided throughthe bearing 18 and the hub 14 to receive drive tangs 22 which are partof a fluid pump mechanism whereby when the impeller 10 is rotated in usein an automatic transmission mechanism the hub portion 14 thereof willdrive the pump member 22 to pump fluid pressure in response to drivingof the engine.

FIG. 2 is a perspective view illustrating the hub portion 14 of impellermember 10 and in particular illustrating the drive slots 20 which areformed on opposite sides of hub portion 14 through both the sheet metalhub portion 14 and the bearing 18.

The bearing 18 is secured to the sheet metal annular impeller 10 by theunique process described herein which incorporates both drawing andextruding of the hub portion 14 to make the assembly.

Referring to FIGS. 3 and 4 there is illustrated a die mechanism 30 whichincludes a support member 32 adapted to receive the member 12 therein insemifinished form. The die mechanism 30 includes a base support member34 and bushing locaters 36. A punch member 38 is illustrated in FIG. 3in position above the die mechanism 30 and carries a hardened steel orcarbide extruder ball 40. As illustrated in FIG. 3, in the manufacturingprocess of the assembly the member 12 is placed in the die member 30 insemifinished form in that the hub portion 14 is not completely finishedbut is in a substantially conical or tapered form. Received within abore 42 in the support member 32 is the hardened thin-wall cylindricalsteel bearing 18 which is to be assembled to hub portion 14. Bearing 18has preformed therein the slots 20 which are engaged by the locaters 36to locate the hardened bearing within the die member.

The unique manufacturing method of the present invention thus comprisesthe following steps: (1) the generally annular sheet metal member 12 ispreformed to the semifinished form illustrated in FIG. 3, (2) thecylindrical bearing member 18 is manufactured including slots 20 thereinand is assembled in the die member 32 with the notches engaging locaters36, (3) the member 12 is then assembled in the die with the semifinishedhub portion 14 thereof being received within the internal diameter ofthe cylindrical bearing 18, (4) a hardened steel or carbide ball 40 ismoved through the internal diameter of the hub portion 14 to finishdrawing the hub portion 14 while at the same time extruding the hubportion 14 into the hardened cylindrical bearing 18, (5) the outer mostextending portion 50 of hub portion is then cut or trimmed off to matchthe length of bearing 18, and (6) the slots 20 are then punched or cutto match the drive slots 20 in bearing 18.

It should be noted that the trimming and cutting operations of steps (5)and (6) above are not illustrated in the drawing since such steps arewell known in the art and a variety of mechanisms can be utilized tocarry out such steps.

It will be seen that in comparing the section thickness of hub portion14 in FIGS. 3 and 4, not only is the hub portion 14 drawn to the desiredfinal shape, but in the process thereof the hub portion 14 is extrudedin that the section, as illustrated in FIG. 4, is thinner than thatillustrated in FIG. 3 and in addition during the extruding process thehub portion 14 is expanded into extremely tight engagement with thehardened cylindrical bearing 18 forming a permanent assembly therewith.If desired, a knurled surface can be provided on the internal diameterof the hardened cylindrical bearing 18 which will enhance the securingof the bearing on the hub portion 14. Of course, by sizing the ball 40to the proper dimension, the exact internal diameter of the hub portion14 is determined without any further forming operations.

The product of the above unique method of manufacture is an improvedsheet metal impeller for a hydraulic torque converter with a hub that isdrawn and extruded to size and having assembled thereto a thin walledhard cylindrical bearing and including drive slots 20 formed on the endthereof to conveniently be engaged by mating tangs 22 of a pumpmechanism for pumping fluid by means of the impeller member 10. Thus, animpeller 10 can be manufactured from sheet metal to provide economy ofmanufacture while at the same time the hub portion of the completedimpeller has a wear resistant surface.

It should be noted that the slots 20 can be formed in the bearing 18 andhub 14 after assembly by known metal cutting techniques. In addition, asused in some transmissions, the pump drive is by flat surfaces formed onthe hub and engaging in a mating configuration in the pump drive member.If such is the case, the present invention can still be utilized toextrude the hub 14 into the shape of bearing 18 if same has flatsections formed in the end thereof rather than slats.

Various of the features of the invention have been particularly shownand described, however, it should be obvious to one skilled in the artthat modifications may be made therein without departing from the scopeof the invention.

We claim:
 1. An impeller assembly for a hydraulic torque converterconstructed of sheet metal and having an axially extending hollow hubportion integral therewith adapted to be connected to drive a fluidpump, the hub member having a thin wall cylindrical bearing memberthereon, the bearing member being secured to the hub portion so as torotate therewith by extrusion of the hub through said bearing, saidbearing member providing a wear resistant surface on the sheet metal hubsurface.